6. The birth and development of pocket metallurgy

At the end of the Second World War, the processing of liquid steel outside the melting furnace was limited to two very specific types of application:

• vacuum degassing of special steels, mainly to eliminate hydrogen, the cause of brittle fractures;

• stirring of steel during ladle casting with a separately melted deoxidizing and desulfurizing slag: the Perrin process used mainly by Ugine .

In the early 1950s, trials of ladle stirring by neutral gas injection, using porous plugs placed at the bottom...